6/02/2010 @ 12:55PM

Chemicals, Cancer And Claptrap

President Barack Obama’s cancer panel has recently released a report on the supposed causes of cancer and how to avoid them. The subject is important–cancer is the second leading cause of death in the United States–and the report could have been useful. Instead it is a travesty, a paragon of political correctness and unscientific, naive speculation and misinterpretation.

The 200-page document produced by the “panel”–which consists entirely of two scientists lacking expertise in cancer epidemiology–is a rehash of myths and misapprehensions about the causes of cancer. The report concluded that “grievous harm” results from exposure to chemicals and that there is “a growing body of evidence linking environmental exposures [to chemicals] to cancer.”

If the authors had only bothered to consult a standard textbook on cancer epidemiology, they would have learned that lifestyle factors such as smoking, obesity, excessive alcohol consumption and overexposure to sunlight–not chemicals in air, water and food–are the underlying causes of most preventable human cancers.

They could also have referred to the summary statement from one of their own previous meetings, “Strategies for Maximizing the Nation’s Investment in Cancer,” held in San Diego in 2007, which concluded: “Similar to the previous meeting in this series, participants stressed that the greatest reduction in cancer mortality could be achieved by eliminating tobacco use; they vocalized disappointment in the lack of political will to eradicate this killer. Smoking remains the single largest preventable cause of cancer. … Significant impact on morbidity and mortality could also be achieved by ‘following the evidence’ and applying what we know–screening and early detection of cancer; better preventive interventions and treatments for those cancers with the highest morbidity and mortality (e.g., breast, colon, lung, prostate); and expanded access to cancer care.”

But instead of following the available evidence, the current panel relied on several specious premises.

First, it assumed that chemicals, by definition, are dangerous, and that our exposure to them should be limited, even at huge cost. That is puzzling because all things, natural and synthetic, including our own bodies, are composed of chemicals.

Second, it assumed that the goal of cancer prevention should be to eliminate all exposure to toxic and carcinogenic agents. The very idea is puerile, not to mention impossible. Safe, natural foods are replete with toxins. Nutmeg contains myristicin, which in high doses can induce convulsions, palpitations and generalized body pain; licorice has glycyrrhizic acid, which if consumed in large amounts can give rise to dangerously high blood pressure; soy-based products such as tofu contain high levels of plant-based estrogens that could affect hormonal balance.

Many foods also contain carcinogens–chemicals that cause cancer at high dose in laboratory animals–such as safrole in cinnamon. The American Council on Science and Health has actually constructed a “holiday dinner menu” of common foods that are replete with toxins and carcinogens.

Third, the panel appeared to be oblivious to the critical relationship of dose–as expressed in the classic toxicological principle “the dose makes the poison”–to risk. Exposure to chemicals like vinyl chloride at high levels for long periods of time did indeed, decades ago, cause cancer in the workplace, as did chimney sweeps’ exposure to soot. The existence of such true human carcinogens is detected via careful collection of epidemiological data, but those high levels of occupational exposure are quite different from environmental exposure to trace levels of chemicals.

Fourth, the panel relied on and endorsed the so-called precautionary principle, which puts the burden of proving what amounts to absolute safety on the makers and purveyors of almost any product. It is not a principle at all but merely a highly risk-averse, unrealistic philosophical premise demanding that every activity and product be proven safe before it is undertaken or used. But how can you prove anything is completely safe? It amounts to trying to prove a negative. Critics can always say you didn’t test in enough species, or for long enough, or at a high enough dose.

A perfect example of the shortcomings of the precautionary principle is the concern raised in the report about the chemical BPA. BPA is a ubiquitous industrial chemical that is essential in the manufacture of many hard plastic products, and it has been used in the lining of cans to prevent the development of foodborne illnesses like botulism. BPA has been used for more than half a century and has been subject to thousands of safety evaluations, with expert panels from around the world (including our own Food and Drug Administration and Environmental Protection Agency) concluding it is safe as used. Yet the panel still raises anxieties about supposed risks. In other words, in spite of all the studies, under the panel’s “precautionary principle,” BPA still does not qualify as “safe.” According to that standard, what chemical could?

The president’s cancer panel’s report is an assault on the science that underlies cancer epidemiology. Some of its recommendations–such as avoiding environmental cancer-causing agents by taking off your shoes and leaving at the doorstep the “carcinogens” you picked up on the way home–are ludicrous. By distracting Americans from proven cancer risks, they will more likely increase rather than decrease our nation’s cancer burden, to say nothing of the public’s anxiety.

This prestigious-sounding panel offers advice that owes more to celebrity-babble on Oprah than to sound science: Eat organic foods, filter your water, use only ceramic or glass, rather than plastic, in the microwave. However, according to the National Cancer Institute’s statistics, smoking accounts for 29% to 31% of cancer deaths, diet for 20% to 50%, infectious disease for 10% to 20%, ionizing and ultraviolet light for 5% to 7%, occupational exposure (from high dose exposures to vinyl chloride, benzene, etc.) for 2% to 4% and pollution (such as radon gas) for 1% to 5%.

The truth is that few chemicals are as toxic as the report of the president’s cancer panel, which will only fuel the Obama administration’s and activists’ ill-advised, unscientific vendetta toward chemicals.

Henry I. Miller, a physician and molecular biologist, is a fellow at Stanford University’s Hoover Institution. He writes a bi-weekly column for Forbes.

Elizabeth Whelan is president of the American Council on Science and Health.